Prepared in cooperation with National Park Service Sample Descriptions and Geophysical Logs for Cored Well BP-3-USGS, Great Sand Dunes National Park, Alamosa County, Colorado SP Neutron Gamma Resistivity Elevation 0 0 7,549 ft 0 16-in. (2,301 m) normal From induction tool 50 50 20 100 100 40 150 150 Depth in feet Depth in feet Depth in meters 60 200 200 250 Electrical 250 ? conductor 80 300 300 100 -50 0 500 1,000 1,500 100 200 10 100 1,000 mV cps cps ohm-m Data Series 918 U.S. Department of the Interior U.S. Geological Survey Cover. Selected generalized geophysical logs and generalized lithologic logs for BP-3-USGS. Photographs from top to bottom: At the end of a core run, the barrel is lifted out of the hole onto one of the several sawhorse setups. Clay from the same sample as in A after almost 5 years of storage in a plastic bag. Stream of water that was flowing out of the drill stem into the mud pool the morning of September 17, 2009. Clay with blue tint at time of collection as a core catcher sample at 266 ft depth (core run 19). B, Clay with even-gray color at time of collection from ≈311 ft depth (core run 26). Intact core after extrusion onto a split half of polyvinyl chloride pipe on a sawhorse apparatus. Sample Descriptions and Geophysical Logs for Cored Well BP-3-USGS, Great Sand Dunes National Park, Alamosa County, Colorado By V.J.S. Grauch, Gary L. Skipp, Jonathan V. Thomas, Joshua K. Davis, and Mary Ellen Benson Prepared in cooperation with National Park Service Data Series 918 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia: 2015 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Grauch, V.J.S., Skipp, G.L., Thomas, J.V., Davis, J.K., and Benson, M.E., 2015, Sample descriptions and geophysical logs for cored well BP-3-USGS, Great Sand Dunes National Park and Preserve, Alamosa County, Colorado: U.S. Geological Survey Data Series 918, 53 p., http://dx.doi.org/10.3133/ds918. ISSN 2327-638X (online) iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Regional Setting and Geophysical Studies ...............................................................................................3 Drilling Operations .........................................................................................................................................4 Procedures for Lithologic Descriptions .....................................................................................................6 Sampling Procedures ...........................................................................................................................6 Mud Stream Samples ..................................................................................................................6 Core Barrel Samples ...................................................................................................................6 Effects of Storage and Handling ......................................................................................................10 Laboratory Methods ...........................................................................................................................13 Sample Descriptions Versus Well Depths ......................................................................................13 Geophysical Logs .........................................................................................................................................16 Logs Acquired......................................................................................................................................16 Data Processing ..................................................................................................................................16 Check of Depth Calibration ......................................................................................................18 Normal Resistivity Logs ............................................................................................................21 Induction Log ..............................................................................................................................21 Density and Sonic Logs ............................................................................................................21 Digital Log Files ...................................................................................................................................26 Summary of Findings ...................................................................................................................................26 Significance for Future Studies .................................................................................................................28 Acknowledgments .......................................................................................................................................30 References Cited..........................................................................................................................................30 Figures 1. Map showing location of BP-3-USGS well, the inferred limit of the last high stand of Pliocene and Pleistocene Lake Alamosa before its disappearance and the Hansen Bluff core site near Great Sand Dunes National Park and Preserve in Alamosa County of southern Colorado ......................................................................................................3 2. Photographs of drilling operations ............................................................................................5 3. Photographs of various sampling procedures for mud stream samples ............................8 4. Photographs of various sampling procedures for core barrel samples .............................9 5. Photographs of a selected core at time of collection compared to more than 4 years later .................................................................................................................................11 6. Photographs of two clay samples of differing color at time of collection in September 2009 compared to almost 5 years later in August 2014 ....................................12 7. Graphical summary of lithologic descriptions and other observations versus inferred well depth .....................................................................................................................14 8. Diagram showing borehole diameter measured by the three-arm caliper and low-pass-filtered, natural gamma-ray curves from five different tools ............................19 9. Diagram showing comparison of original neutron curve to induction and spontaneous potential logs to correct the depth scale for the neutron log .....................20 iv 10. Diagram showing normal resistivity curves from the multiparameter tool before and after data processing .................................................................................................................22 11. Diagram showing resistivity derived from the induction tool before and after data processing compared to normal resistivity curves after data processing .......................23 12. Diagram showing resistivity curves after data processing compared to resistivity layers derived from a time-domain electromagnetic sounding measured at the site before drilling ..............................................................................................................................24 13. Diagram showing sonic velocity and compensated density logs ......................................25 14. Diagram showing selected geophysical logs and generalized lithologic log for BP-3-USGS ...................................................................................................................................27 Tables 1. Explanation of and procedures for different sample types ...................................................7 2. Core lengths recovered onsite in 2009 and changes in measured lengths in years 2012 and 2013 ...............................................................................................................................10 3. Geophysical tools and associated data logs acquired for BP-3-USGS, listed in the order they were acquired ..........................................................................................................16 4. Description of geophysical logs and their utility for BP-3-USGS .......................................17 5. Overview of data processing steps applied to geophysical logs